Taking the example of the clothing industry, garment production is usually organized around a cutting workshop equipped with at least one cutting machine operating on a lay-up in compliance with a predetermined layout, and a manufacturing or assembly workshop in which the cut-out pieces are assembled together and stitched together, and the resulting garments are finished.
The products resulting from cutting up the lay-up must be processed to enable them to be used by the manufacturing workshop.
In particular, it is necessary to separate the stacks of cut-out pieces from the offcuts. The offcuts constitute the stencil-like remaining “skeleton” of the lay-up, i.e. the portion of the lay-up that is complementary to the stacks of cut-out pieces. It can also be necessary to sort, to identify and/or to wrap the stacks of cut-out pieces so as to constitute coherent batches before they are conveyed to the manufacturing workshop.
It is common for the operations of separating the stacks of cut-out pieces from the skeleton of the lay-up, and of sorting the cut-out pieces to be performed manually by an operator. To help the operator to distinguish between the stacks of cut-out pieces and the portions of the skeleton, it is often necessary for each stack to be marked in order to be identified easily.
Procedures have been considered for enabling the stacks of cut-out pieces to be separated from the skeleton of the lay-up automatically.
Thus, U.S. Pat. No. 5,101,747 proposes an installation in which the skeleton of the lay-up is taken away at the outlet of the cutting station by being pulled upwards out of the horizontal path of the lay-up, while a roller presses the lay-up to help the stacks of cut-out pieces to separate from the lay-up and to fall under gravity into a collector bin. Unfortunately, it is necessary to stitch the pieces of each stack together to prevent the stacks from falling apart. It is also necessary to sort the collected stacks of pieces, and that can require marking the stacks in order to assist an inexperienced operator or when the pieces are similar in shape. It is also necessary for the lay-out of the pieces to be cut out to be such that it leaves the skeleton of the lay-up in one piece, which requires the pieces to be spaced apart sufficiently from one another and from the edges of the lay-up, and therefore prevents the material from being used optimally.
U.S. Pat. No. 5,092,829 proposes inserting link members into the stacks of cut-out pieces and picking up the stacks of pieces by means of a robot arm suitable for grasping the link members as engaged through the pieces. The movements of the robot arm are controlled by a control unit as a function of stored information relating to the locations of the stacks of pieces in the lay-up. Unfortunately, that system suffers from the major drawback of requiring a link member, e.g. a serrated rod to be inserted into the stacks of pieces. In many cases, this results in the material being damaged unacceptably.